Evacuation system



M y 2 1933- P. L. SPENCER 1,9 6 653 EVACUATION SYSTEM Filed March 15,1928 B6230 L.. p6iml" r Patented M 1 3 PIIBCY L; SPENCER, or" MEDFOBD,MASSACHUSETTS, ssIG CAMBRIDGE, MASSACHUSETTS, A coRroa 'rIoN or Non 'rroRAiTHEON inc; or 1.

MASSACHUSETTS I nvAcvArrorr sys'rmr 7 Application med March 1928. serial m. 261,977.

The invention relates broadly to themanufacture of space current devicesand in particular to an improved method of treating the electrodes.

5, Heretofore,

the evacuation process in .order'to remove gases, occluded m the metaleither by passing a bombarding discharge between them or inducing acurrent in one or more of the metallic bodies by an externally locatedcoil. For electrical bombardment, there has been employed direct currentof polarity such as to impel the discharge toward the electrode ofconsiderable 15 metal content, usually the positive member. While theanode treatment by direct current is satisfactory in case thecooperating electrode holds littleor no gas in occlusion, e; g.

a filamentary cathode, and for that reason requiring no preliminaryheating, it fails to offer a double way bombardment in the event thecathode constitutes a nonthermionic 'member or has large mass. Moreover,in apparatus involving two; or more cathodes or anodes, prior art offersno automatic shift of bombarding ous combinations treatments ofdifferent degrees. I i a An object of my invention is to provide asimple, inexpensive and effective method of heat treatingelectrodes,and,,in general, to improve the manufacture and operation ofgaseous conduction apparatus.

i In the drawing which illustrates a: preferred embodiment, numeral 1designates the device undergoing'the process of .manufacture. Thisdevice may compriseanyform of space current apparatus; forconvenience, I40 show a rectifier of the Raytheon type BH socalled such as describedand claimed inihe applications of Smith, Serial No. 526,095 and it hasbeen customary during S to heat the electrodes.

- heat each of theelectrodes and accordingly discharge between the vari.

of electrodes with the re-; sult that the elements are subjected to heatI impurities. The illustrated rectifier comprises an envelope 2 terminting in reentrant stem 3 from which two glass] tubular members 4 project; Fitting over the proj ections,"there are insulating thimbles,5ioflava or the like having a relatively fine bore through which theanodes 6.6 of refractory wmetal extend. About'the latter, a hollowcathode? of re fractory metal is mounted, said cathodehaving ahemispherical, conical or other shape, and closed along the horizontalplane .by cover8,preferably of the same metal-as the cathode. Asexplained in the applications supra, a device such as described offersless impedance fo'rcurrent passing from the anode to the'cathode thanvice versa and is adapted for ,rectifyingalternating current ofrelatively-low voltage,'=e. 'g. below 200 volts; During ,the evacuationprocess, I propose to provide a polyphase. source of current 9 ofn'ections being,- had :with the electrodes through current limitingresistors l0rand wires 11,12. It will be. evident that the 7 currentsource produces an electrical dis- I charge between each pair ofelectrodes in succession, the electron or ion bombardment beingsuflicient to raise the temperature of the metallic bodies to a pointwhere the occluded f relatively. high potential, e. g; 550 volts,congases escape and pass off to the evacuat ng pump.

Experience has shown that when using ly regulated by the current supply,accord- 1 ing uniformity of-treatment to ea ch elec-, trode and'also tothe device as a whole. heat treatment and the evacuation ofoc eludedgases having been completed, a hy- 5 dr'ogen washmay be employed whileon the m a The ;f

1. In the manufacture of a gas discharge I device of the type comprisingan evacuated envelope enclosing a large-area cathode and,

a plurality of small-area anodes, and an atmosphere of an inert gas, themethod of depriving said electrodes of occluded gases which comprisesconnecting said cathode and said anodes to the individual phases of apolyphase alternating current source and maintaining a polyphase spacecurrent discharge between said electrodes While simultaneouslyevacuating said envelope.-

2. In the manufacture of a gas discharge device of the type comprising acathode having an extended discharge surface and a plurality of anodes,each of said anodes having a small discharge surface, said anodes andcathode being presented to a common discharge space, and an atmosphereof an inert gas in said discharge space, the meth- 0d of depriving saidelectrodes of occluded gases Which comprises connecting said cathode andsaid anodes to the individual phases of a polyphase alternating currentsource, and maintaining a 'polyphase space current discharge in saiddischarge space be tween said electrodes While simultaneously evacuatingsaid envelope.

In testimony whereof, I have signed my name to this specification this13th day of March, 1928.

PERCY L. SPENCER.

